Electric–magnetic symmetry and Noether's theorem

Cameron, R.P. and Barnett, S.M. (2012) Electric–magnetic symmetry and Noether's theorem. New Journal of Physics, 14, p. 123019. (doi:10.1088/1367-2630/14/12/123019)

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Abstract

In the absence of charges, Maxwell's equations are highly symmetrical. In particular, they place the electric and magnetic fields on equal footing. In light of this electric–magnetic symmetry, we introduce a variational description of the free electromagnetic field that is based upon the acknowledgement of both electric and magnetic potentials. We use our description, together with Noether's theorem, to demonstrate that electric–magnetic symmetry is, in essence, an expression of the conservation of optical helicity. The symmetry associated with the conservation of Lipkin's zilches is also identified. We conclude by considering, with care, the subtle separation of the rotation and boost angular momenta of the field into their 'spin' and 'orbital' contributions.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Barnett, Professor Stephen
Authors: Cameron, R.P., and Barnett, S.M.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:New Journal of Physics
Publisher:Institute of Physics Publishing Ltd.
ISSN:1367-2630
ISSN (Online):1367-2630
Copyright Holders:Copyright © IOP Publishing Ltd.
First Published:First published in New Journal of Physics 14:123019
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
549871Challenges in Orbital Angular MomentumMiles PadgettEngineering & Physical Sciences Research Council (EPSRC)EP/I012451/1P&A - PHYSICS & ASTRONOMY